Scottish Secretary Alistair Carmichael and Angus Robertson are giving speeches on the matter of Scottish independence and European Union membership(Reuters)

Two of Scotland's highest profile politicians will each deliver speeches today setting out opposing prognoses for Scotland's membership of the European Union.

Scottish Secretary Alistair Carmichael is in Brussels to give a speech at the Centre for European Policy Studies where he will say that Scotland's interests in the EU are best served by being part of the United Kingdom.

Meanwhile, the Scottish National Party's leader at Westminster, Angus Robertson, will deliver a rival speech in Dublin at the Institute of International and European Affairs (IIEA), where he will make the opposite case.

Pro and anti-unionist campaigners are locked in a bitter ideological struggle as they campaign to win hearts and minds of voters ahead of the referendum on Scottish independence in September.

Carmichael's speech will extend the argument made British government officials published on the 17 January, which stated that an independent Scotland in Europe could be up to £3.8bn (€4.6bn, $6.2bn) worse off once denied access to the UK's rebate. Carmichael will also attack the SNP's timetable to become an EU member.

According to the SNP's document, Scotland's Future, published in November 2013, Scotland can become a member of the EU within 18 months of gaining independence.

Carmichael will say: "The 18-month timetable the First Minister proposes to place both on himself and the rest of the EU is a negotiating position of extraordinary weakness.

"One man's obsession to deliver independence not just to a specific timetable, but to a specific day of the week, would not just undermine Alex Salmond's hand in negotiations, but Scotland's future in Europe.

"Instead of showing he has Scotland's interests at heart, this obsession with a date rather than the deal reveals just how much of a vanity project this really is.

"Of course the reality is that the terms of membership could not be known until such a time as they were agreed.

"But the Scottish Government is morally bound to set out in detail what terms of membership they would seek and we are all entitled to assess just how likely this is to happen."

However, Robertson will make the opposite case and is expected to say: "Independence will mean Scotland taking its place in the international community and playing a positive proactive international role.

"Scotland will be a trusted security partner for our allies, play a full role in the Commonwealth, properly fulfil our international development responsibilities and we have an ambition to fully support peace and reconciliation efforts around the world."

Robertson's speech will echo the arguments of two prominent Scottish politicians, deputy first minister Nicola Sturgeon and the Scottish government's cabinet secretary for rural affairs and the environment, Richard Lochhead: both have said Scotland loses out on the benefits of EU membership.

One of these areas is the common agricultural policy (CAP) where the SNP has said the British government damages the interests of Scottish farmers by not giving them their fair share of EU funds.